1. Field of Invention
Aspects described herein relate to processing devices and methods of fragmenting materials such as nucleic acids. In some instances, processing devices may include a shearing region for fragmenting nucleic acids or other macromolecules in a sample upon suitable flow of the sample through the shearing region.
2. Related Art
Pumping a liquid solution into and through a small hole or capillary has been known to create strong velocity gradients in the solution. For solutions that contain DNA, such velocity gradients result in shearing forces that fragment DNA within the solution. A number of applications employ a pump to push and pull solutions having DNA through a small hole; however, such implementations can give rise to a number of issues. Existing systems that utilize pumping methods to push and pull liquid samples of DNA through small capillary holes can not only be expensive, but are highly susceptible to loss of DNA samples as well as cross contamination. Further, pumping a DNA sample to travel back and forth through a small hole can also be a slow and involved process.
For example, in some systems, a DNA solution is pushed from an inlet into a shearing orifice with a syringe where the solution is repeatedly pushed and pulled within the shearing orifice approximately 20 times. This process can take up to 20 minutes and is performed only on a single liquid solution of DNA at a time. Further, use of a syringe to push and pull a DNA solution within a shearing orifice gives rise to void volumes where a portion of the original solution is lost. Clogging of the orifice is also known to occur, resulting in leakages due to pressure in the flow tubing which can also lead to certain amounts of lost solution. Because cross contamination in shearing systems when samples are used in sequence presents an issue, the systems will often require washing steps which can not only be time consuming, but does not ensure that contamination will be prevented. Existing systems that cause movement of a sample of DNA through a shearing orifice are unable to regulate the pressure and flow rate through the system (e.g., establishing and maintaining a pressure at the entrance region to the shearing orifice), leading to undesirable results.